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Re: [SQL] HAVING in EXISTS-clause ...

From: wieck(at)debis(dot)com (Jan Wieck)
To: marten(at)feki(dot)toppoint(dot)de
Cc: tgl(at)sss(dot)pgh(dot)pa(dot)us, pgsql-sql(at)postgreSQL(dot)org
Subject: Re: [SQL] HAVING in EXISTS-clause ...
Date: 1999-11-13 03:17:30
Message-ID: m11mTgw-0003l1C@orion.SAPserv.Hamburg.dsh.de (view raw or flat)
Thread:
Lists: pgsql-sql
>
> Hello all out there,
>
> > involving aggregate functions as sub-selects in FROM.  So it's probably
> > not worth any effort to add more code to a routine that shouldn't exist
> > in the first place; we've got to work on the fundamental problem
>
>  What makes me nervous is the fact, that I've seen limitations with
> the length of the sql statements, some hidden problems here and there
> and we want to use PostgreSQL in a research projects the next year
> and we're writing now some oo->rdbms mapper software and therefore
> we produce some "non-typical" statements and see those limitations
> (and perhaps even better: some are not documented).

    Nervous or not, Tom is right!

    Some  people  seem  to  forget  that Postgres initially was a
    PostQUEL  database.  After  the  original  Berkeley   project
    terminated,  it  became  a SQL database and (sometimes) later
    called PostgreSQL.

    The PostQUEL query language was way simpler than SQL. All the
    internal structures of Postgres where optimized to match this
    language.

    We need to change a detail in  the  parser/rewriter  now,  to
    meet the needs of our new language. This requires changes not
    only in the parser and rewirter,  the  planner/optimizer  and
    maybe  the  executor need changes too.  Usually, this kind of
    vertical change takes some time in open source projects.

    But it doesn't help to continue doing cosmetic changes on the
    symptoms.  Sometimes you have to attack the initial problems,
    and this time is now.


Jan

--

#======================================================================#
# It's easier to get forgiveness for being wrong than for being right. #
# Let's break this rule - forgive me.                                  #
#========================================= wieck(at)debis(dot)com (Jan Wieck) #



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